The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Opposition environment spokesman Mark Butler said a "spectacular" move by China to introduce a nation-wide emissions trading scheme showed only Labor would "get with the rest of the world" with a similar policy.

Many Australians had hoped Mr Turnbull would "drag his party back to the sensible centre on climate change" and commit to his previously-preferred ETS but had their hearts broken when the prime minister committed to the existing direct action policy, Mr Butler told reports in Casino on Saturday.